Dozens of fire fighters are battling a fire near the town of Karystos, on the island of Evia, east of Athens.
The fire that broke out late on Thursday is not currently threatening any homes, the fire service says.
At least 57 firefighters with 23 vehicles, aided by two water-dropping aircraft and a helicopter, are trying to contain the blaze.
In August a wildfire in central Evia destroyed vast swaths of a large pine forest, listed as a Natura 2000 protected area.
The burned area is estimated to be between 2,000 and 2,800 hectares of land (20,000-28,000 stremmas, or 6,919 acres).
Meanwhile, another wildfire has also broken out at Lagadakia, on the island of Zakynthos.
The chief of Ionian Islands Fire Brigade, Andreas Rizos, told the Athens-Macedonian News Agency that the blaze is burning a forest there at the present time.
There is no information on whether or not nearby villages are currently threatened by the fire.